HR: 14:40h
AN: U52B-05    [PDF]
TI: Biomarkers Indigenous to Late Archean Rocks
AU: * Eigenbrode, J L
EM: eigenbro@geosc.psu.edu
AF: Penn State University, Department of Geosciences, University Park, PA 16802 United States
AU: Freeman, K H
EM: kate@essc.psu.edu
AF: Penn State University, Department of Geosciences, University Park, PA 16802 United States
AU: Summons, R E
EM: rsummons@mit.edu
AF: Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, Cambridge, MA 02139 United States
AU: Love, G D
EM: glove@mit.edu
AF: Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, Cambridge, MA 02139 United States
AU: Snape, C E
EM: colin.snape@nottingham.ac.uk
AF: University of Nottingham, School of Chemical, Environmental, and Mining Engineering, Nottingham, NG7 2RD United Kingdom
AB: Two new lines of evidence support the authenticity of molecular fossils in late Archean rocks of the Hamersley Province, Western Australia. Specifically, they support 1) a syngenetic relationship between the kerogen and extractable biomarkers, and 2) a indigenous relationship between extractable compounds and the host rocks. Carbon skeletons released from kerogen via high-pressure hydropyrolysis match those found in associated extracted bitumen. Biomarker ratios indicate less mature steranes and terpanes (i.e. hopanes and tricyclic terpanes) are embedded in the kerogen matrix as compared to the highly mature steranes and terpanes in the extracts, which is similar to findings in other hydropyrolysis experiments. Lithology-associated variations in biomarker distributions are noteworthy and suggest environmental settings are associated with differing biotic ecosystems. The evidence reported here confirms the 2.7 Ga antiquity of diverse biosynthetic pathways. Molecular data, together with isotopic data, indicate aerobic and anaerobic respiration pathways were fundamental to the complex microbial biogeochemistry of the late Archean. The biomarkers in these rocks support an early radiation of the three domains of life and radiation within the bacteria, such that clades of cyanobacteria, green sulfur bacteria, and proteobacteria had been established.
DE: 0400 Biogeosciences
DE: 1060 Planetary geochemistry (5405, 5410, 5704, 5709, 6005, 6008)
DE: 1615 Biogeochemical processes (4805)
DE: 8125 Evolution of the Earth
SC: U
MN: 2003 Fall Meeting